#include <stdio.h>
int Fibonacci(int num){
	if(num == 1||num == 2)
		return 1;
	else
		return Fibonacci(num - 1) + Fibonacci(num - 2);
}
int main(){
	int num = 0;
	scanf("%d",&num);
	printf("%d",Fibonacci(num));
	return 0; 
}

